1. Field of the Invention
The present invention generally relates to a voltage divider circuit, and more particularly, to a voltage divider circuit adapted for a thin film transistor display (TFT LCD).
2. Description of Related Art
In the driving circuit for TFT LCDs, each source driver IC (integrated circuit) needs a set of DC voltages ranging from a low level to a high level, called a divided voltage. FIG. 1 depicts a voltage divider circuit 100 implemented in a current notebook computer, wherein a voltage is first divided by a plurality of first resistors R1 connected in series, and after the divided voltage passes through a buffer B consisting of operational amplifiers, the divided voltage is further divided into 10 voltage levels that range from V1 (low voltage) to V10 (high voltage) by a plurality of resistors R2. Next, these 10 voltage levels are input to the source driver ICs S1-S8. As the number of buffers B implemented in the circuit is small, manufacturing cost is accordingly lowered; however, the divided voltages are not easily adjusted because they are easily affected by the internal resistances in the source driver ICs S1-S8.
On the other hand, FIG. 2 depicts a conventional voltage divider circuit 200 implemented in the current TFT LCD panel, wherein a voltage is divided by a plurality of first resistors R connected in series, and after the divided voltage passes through a buffer B, 18 divided voltages with voltage level ranging from V1 TO V18 are obtained and then input to the source driver ICs S1-S10. In addition, the voltage divider circuit 200 employs more buffers to overcome the drawbacks of the voltage divider circuit 100, but the manufacturing cost is accordingly increased.
The objective of the present invention is directed to a voltage divider circuit that have the advantageous of the preceding two voltage divider circuits 100 and 200.